The invention relates to a portable tool especially adapted for the cleaning, deburring, burnishing, and the like of the ends of conduits and fittings that are to be joined to one another. Various kinds of tools for such purpose have been proposed heretofore, but the known tools have disadvantages among which are lack of portability and the inability to function properly on conduits of differing diameters or wall thickness. Tools constructed according to the invention overcome such disadvantages by their being adapted for use with hand-held rotary motors and by being radially expansible and contractile so as to treat not only conduits of different diameters, but also of different wall thickness. In addition, a tool constructed in accordance with one embodiment of the invention is capable of treating simultaneously both the inner and outer surfaces of a conduit or fitting.